Abiru Kobushi is student number 19 in class 2-F, always shown wrapped in extensive bandages. Her name stems from "kobushi abiru," meaning "to bathe in fists." Early rumors blamed her injuries on paternal violence, but her homeroom teacher uncovered her zoo employment. The wounds result from animal attacks incurred while indulging her tail fetish—a compulsion to pull animal tails despite danger. She owns a large collection of mounted tails, typically dismissing them as replicas when displaying them.

Physically, she appears skinny and pale, with black shoulder-length hair in braids. She has heterochromia iridum: her right eye is brown, while her left remains obscured by a corneal transplant. Her bandage coverage varies. Notably, her extremely flexible hip joints allow poses like an internally over-rotated wariza without discomfort, even as she fixates on minor injuries like a sprained finger. Her dry, stoic demeanor masks intense enthusiasm for animal tails and deep admiration for her teacher, often delivering blunt remarks in a monotone.

Key events include her introduction revealing the tail obsession as her injury source and an attempt to attach a tail to her teacher. Later chapters expose her corneal transplant, enabling vision of the donor’s fatal accident license plate. Her bandages aid in locating her kidnapped teacher. She briefly kidnaps classmate Mikoto as a "pet" before freeing him, later kidnapping multiple individuals’ "tails." A moment occurs when her facial bandages tear, hinting at an undisclosed truth. The transplant’s origin is finally revealed in the conclusion.

Her aspirations include becoming a veterinarian and traveling worldwide to pull every animal species’ tail, ranking chipmunk tails first, followed by Bengal tiger and green python. After a detoxification event, her injuries heal temporarily, fully revealing her face and left eye—though the transplant’s origin remains unexplained until the finale.